I. Field of the Invention
The present invention relates to infusion control sets for use with a syringe pump or the like.
II. Description of Prior Art
A syringe pump infusion control set may include a three port stopcock by which to selectively connect a bolus injection syringe (such as part of a syringe pump device) to either a bulk source of fluid or a patient. The syringe is coupled to one stopcock port ("syringe port") with a bulk fluid reservoir such as a bottle or bag of medicine coupled to another port thereof ("bottle port" or "supply port") via a length of tubing. The third port ("patient port") is coupled to another tube to connect to a catheter or the like inserted into a patient's circulatory system.
The stopcock normally has at least two positions. In one position, the syringe port is coupled to the bottle port so as to permit filling of the syringe with the medicine from the fluid source. The other position of the stopcock couples the syringe port to the patient port so as to permit controlled infusion of the medicine from the syringe or other pump to the patient. In this way, small boluses of medicine may be administered to the patient under control of the syringe while maintaining a bulk supply of fluid available for refilling the syringe without opening the system to atmosphere such as by removing the syringe or catheter from the fluidic system connected to the patient. To avoid the risk of the bulk source of fluid coupling, directly to the patient, the stopcock may have a limited range of motion such that the bottle port is never fluidically coupled directly to the patient port.
While the stopcock-based sets have the advantage of allowing the syringe to be refilled and used for bolus injections without disconnection of the system, there is the disadvantage of requiring manipulation of the stopcock for proper use. To overcome that disadvantage, it has been proposed to replace the stopcock with an automatically-responding junction device having normally closed, high cracking valves forming an integral part of each of the bottle and patient ports. The valved junction has the advantage that actuation of the syringe either to fill or inject automatically opens and closes the respective valves to accomplish the proper port selectivity. Thus, pulling on the syringe plunger creates a high negative pressure within the junction causing the bottle port valve to open while the patient port valve is held closed so as to allow the syringe to be filled without fluid communication between the bulk fluid source and the patient. Similarly, pushing the syringe plunger in to inject the medicine creates a large positive pressure within the junction against which the bottle port valve remains closed and the patient port valve is forced open to thus inject the medicine into the patient, all without allowing the bottle port to be fluidically coupled directly to the patient port.
While the valved junction syringe pump system is thus easier to use than the stopcock-based system, there are certain drawbacks associated with the valved junction as compared to the stopcock-based system. In particular, with the valved junction, the dynamic response of the system to actuation of the syringe plunger for an injection is less than desirable. By way of example, there is a short period of delay before the patient port valve opens resulting in delayed delivery of the medicine to the patient with possible adverse consequences.